A study of technology for automatically performing at least one of vehicle velocity control and vehicle steering control (such technology is hereinafter called automated driving) has recently been in progress. In relation to this, there is known a technique of letting a driver know the switching of the driving mode by controlling a reclining motor of a subject vehicle so that the reclining angle of a driver's seat in an automated driving mode may be larger than the reclining angle of the driver's seat in a manual driving mode (see International Patent Application Publication No. 2015/011866, for example).